US Defense Chief Ash Carter admits the PYD and its armed wing the YPG have links to the PKK terrorist group.

US Defense Chief Ash Carter admitted on Thursday that the PYD and YPG are linked to the PKK, an armed Marxist-Leninist group listed as a terrorist organisation by Turkey, the US, the EU and NATO.

When asked by Sen. Lindsey Graham whether the PYD and its military wing, the YPG, are aligned with the outlawed PKK terror group during testimony before a Senate panel, Carter replied in the affirmative.

Admitting the link between the PKK and PYD, Carter acknowledged that the PKK is designated as a terror group by the US and Turkey, but denied that Ankara is upset by US air and equipment support to its offshoot in Syria.

"We have extensive consultations with the Turks," Carter added.

But Sen. Graham contradicted him saying that he was recently in Turkey and the government there is not happy with US support for the PYD and its armed wing the YPG, both considered by Turkey as part of the same terror group.

The US, on the other hand, does not consider the PYD and the YPG to be terrorist groups.

"They think this is the dumbest idea in the world and I agree with them," Graham said.

Graham noted that Turkey has been asked by the US to do more in the fight against the DAESH terror group, but he does not believe that the argument by Turkish government is "absurd."

"We are arming people inside of Syria who are aligned with a terrorist group, that is the finding of Turkish government," he said.

Eva Savelsberg, who is the chair of the Berlin-based European Centre for Kurdish Studies, spoke to TRTWorld following Carter's statements. She said that despite the US acknowledging the link between the YPG and the PKK, it is unlikely that the US will cease its support for the group.

"It doesn't seem, at least at the moment, that the US will really change their politics. They will continue to arm the YPG," Savelsberg said.

"If the US government now says YPG and PKK are one organisation, the logical second step would be not the arm the YPG anymore," she added.

Savelsberg also said that as much as half of those in the YPG's ranks are fighters from the PKK in Turkey.

Turkey has long expressed its dismay at US support for the PYD, which Ankara considers to be one and the same as the PKK.

The US, on the other hand, does not consider the PYD and the YPG to be terrorist groups, and considers them key allies in the battle against the DAESH terrorist group in Syria.

The PYD's expansion in northern Syria has been supported by US-led air strikes as they move into territories seized from DAESH.

The Pentagon confirmed last October that its cargo planes dropped "small arms ammunition" for the Syrian Democratic Forces (SDF), which was a newly-formed militant coalition at the time led mainly by the YPG.